The present invention relates generally to an automotive audio speaker which utilizes a vehicle panel as a sound-producing medium. More specifically, the invention relates to a driver unit for an automotive audio speaker, which prevents degradation of the audio sound output level caused by lateral displacement of a vibrating component with respect to a stationary component.
The automotive audio speaker utilizing at least a part of a vehicle panel, such as rear parcel shelf, door inner panel or the like, as a sound-producing medium has been recently developed. Such speakers have the benefit of producing better quality audio sound, especially in the relatively low frequency range.
Generally, such speakers include a driver unit for driving the vehicle panel at audio frequencies. The driver unit includes a stationary component establishing a permanent magnetic field and a vibrating component fixed to the vehicle panel and excited at the audio frequencies by an audio signal fed from an automotive audio system, such as a tape deck, radio receiver or the like. The vibrating component is subject to the magnetic field formed by the stationary component for driving the vehicle panel in response to the audio signal. The stationary component is suspended from the vehicle body by a resilient suspension member.
In such a structure, the vibrating component and the stationary component may tend to be displaced from their optimal spatial relationship with regard to the magnetic field due to movement of the vibrating component lateral to the axial driving direction during vibration.
The invention is to eliminate this drawback of automotive audio speaker driver units in speakers utilizing a vehicle panel as a sound-producing medium. In priniciple, this can be achieved by providing a guide member for allowing axial movement of the vibrating component and restricting lateral movement thereof.